Analysis of genetic variation and population structure among of oregano (Origanum acutidens L.) accessions revealed by agro-morphological traits, oil constituents and retrotransposon-based inter-primer binding sites (iPBS) markers

The genetic associations among 31 oregano (Origanum acutidens (Hand.-Mazz.) Ietswaart) genotypes collected from different provinces of Turkey were determined by comparing their agro-morphological traits, essential oil components and molecular traits. In order to assess the genetic diversity in 9 agro-morphological traits and 9 essential oil components, 10 polymorphic iPBS primers were used. Principle component analysis (PCA) for agro-morphological traits had two axes explaining 81.35% of total variation and PCA for essential oil components had 4 axes explaining 89.67% of total variation. Cluster analysis yielded two main clusters for agro-morphological traits and four main clusters for essential oil components. Present iPBS primers generated 289 alleles. Number of alleles per polymorphic locus varied between 25 and 36 with an average value of 28.40. The average polymorphism ratio was as 98.36%. Polymorphic information content values varied between 0.28 and 0.42. The average number of alleles (ne), Nei’s genetic diversity (h) and Shannon’s information index (I) were obtained 1.61, 0.37 and 0.55, respectively. The 31 accessions were assembled into three main clusters according to the unweighted pair-group mean average based on iPBS markers. Similarity index value varied between 0.51 and 0.81. Moreover, population structure analysis using Bayesian method showed that all genotypes formed eight sub-population (K = 8) with an average value of 0.3544 for expected heterozygosity and 0.0400 for population differentiation measurements (Fst value). In present study, population structure of 31 oregano genotypes collected from different provinces of Turkey were successfully characterized with the aid of iPBS markers and model-based clustering. It was concluded based on present findings that iPBS markers could reliably be used in genetic diversity and molecular analysis of oregano genotypes.